If you are starting out with just a roku or similar media streamer with hdmi interface, here is a very inexpensive yet effective way I have found to do it:
Amazon.com: avedio links 4K@60Hz HDMI Audio Extractor Converter, HDMI to HDMI + Audio ( SPDIF + RCA L/R Stereo ), HDMI Video Audio Splitter Embedder Adapter for Fire Stick, Xbox, PS5, Support 3D, HDCP 2.2, 18Gpbs : Electronics
Amazon.com: avedio links 4K@60Hz HDMI Audio Extractor Converter, HDMI to HDMI + Audio ( SPDIF + RCA L/R Stereo ), HDMI Video Audio Splitter Embedder Adapter for Fire Stick, Xbox, PS5, Support 3D, HDCP 2.2, 18Gpbs : Electronics